Like stealth tigers, billionaires Warren Buffett and Bill Ackman are moving in for the kill of the wounded bond-insurance business – but their ultimate meal could turn mean and messy.

Ackman, 41, has been stalking the bond-insurance companies for years with a strong hunch they’d become broke overnight and would earn him a windfall by betting on their demise.

Buffett, 77, who built a huge fortune on nuts-and-bolts insurance, has coveted the bond-insurance world’s only treasure chest – its ultra-safe bets on municipal borrowing, since local governments almost never go bust.

Both men yesterday won sideline assistance for getting what they’re hunting in at least two of the four major bond-insurance firms on the run.

New York State regulators began beating the bushes more vigorously in financial circles to keep at least the New York-domiciled prey – MBIA and Ambac – on track for the fatal blows.

Those blows would come in the expected split of each bond insurer into two separate companies, based on the risk they insure.

One unit would carry all the bad risk, including junk paper; the other would hold gold-plated risks of municipalities and cash-rich public entities like Port Authority.

New York State Insurance Commissioner Eric Dinallo says he wants the break-up because it would yield at least four healthy companies to serve municipalities and other public debt, and remove the yoke of junk paper dragging down the bond market.

Ackman is making huge bets that stocks of the companies will fall in a break-up. Buffett, meanwhile, wants to snap up the business of the cloned companies carrying only good risks, which fits into his sprawling insurance empire.